If caviar is important to you and/or you want to avoid the limited "Light Bites" menu, avoid flights departing DXB (and other cities) departing between 12AM and 6AM that are under 8-9 hours or have lots of non O&D traffic.

Example: The DXB-PVG, DXB-PEK flights that depart around 3-4AM have caviar, and don't have the "Light Bites menu (these seem to be O&D heavy? these flights are around 7 hours). Meanwhile DXB-HKG departing around 3AM (seems to be connection heavy and has a similar flight length) doesn't have caviar and has the "Light Bites" menu.

Also, on DXB-LHR flights that depart between 6AM to 11PM, all of them serve caviar. However, the 3AM DXB-LHR flight doesn't and instead has the "Light Bites" menu.

If a flight is around 4-5 hours and has F, it is guaranteed to not have caviar.